deepseek-ai/deepseek-harness · error

rpcId mismatch for : sent , got

Error message

rpcId mismatch for ${endpoint}: sent ${rpcId}, got ${full.rpcId}

What it means

Every unary call mints a random UUID rpcId, sends it inside the client-request envelope, and requires the server response envelope to echo it. A mismatch means the envelope answers a different request: typically a caching proxy or service worker replaying a stale response, an interleaving middlebox, or a server implementation that mints its own id instead of echoing the request's.

Solutions

1. If you control the server, echo the request envelope's rpcId verbatim instead of minting one
2. Disable HTTP and service-worker caching for the /api paths the RPC posts to
3. Retry the call once with a fresh id when the operation is idempotent; the stale cached envelope is usually evicted by then

Example fix

// before — server builds its own id
const response = { type: 'server-response', rpcId: RpcId(randomUuid()), result }

// after — echo the request's id
const response = { type: 'server-response', rpcId: request.rpcId, result }

async function callRetrying(rpc, channel, endpoint, payload, attempts = 2) {
  for (let i = 0; ; i++) {
    try {
      return await rpc.call(channel, endpoint, payload)
    } catch (error) {
      if (i + 1 >= attempts || !String(error).includes('rpcId mismatch')) throw error
    }
  }
}

When it happens

Trigger: rpc.call receives a schema-valid response whose rpcId differs from the sent one: HTTP or service-worker caches replaying an old POST response, a proxy mis-correlating concurrent requests, or a hand-written server that forgets to copy rpcId from request to response.

Common situations: A service worker or CDN configured to cache the RPC POST route; devtools offline-replay; a custom server generating fresh ids in the response envelope.

Related errors

• command directory warmup failed
• command.execute failed
• command.list failed
• context-not-found
• conversation.cancel failed

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/8879a23520766791. Report an issue: GitHub.

Appendix: source

Thrown at packages/client/connection/src/client/rpc.ts:49

        rpcId,
        method: endpoint,
        payload,
      }
      const response = await send(
        new URL(`${channel}/${endpoint}`, resolveBase()),
        {
          method: 'POST',
          headers: { 'content-type': 'application/json' },
          body: JSON.stringify(message),
          ...signal === undefined ? {} : { signal },
        },
      )
      if (!response.ok) {
        throw new Error(`transport failure for ${channel}/${endpoint}: HTTP ${response.status}`)
      }
      const full = serverResponseSchema.parse(await response.json())
      if (full.rpcId !== rpcId) {
        throw new Error(`rpcId mismatch for ${endpoint}: sent ${rpcId}, got ${full.rpcId}`)
      }
      return full.result
    },
  }
}

function resolveBase(): string {
  const location = (globalThis as { location?: { origin?: string } }).location
  return location?.origin !== undefined && location.origin !== 'null' ? location.origin : INTERNAL_BASE
}

function assertTarget(channel: string, endpoint: string): void {
  const segments = endpoint.split('/')
  if (!CHANNEL_PATTERN.test(channel)
    || segments.some(segment =>
      segment === '' || segment === '.' || segment === '..' || !ENDPOINT_SEGMENT_PATTERN.test(segment))) {
    throw new Error(`connection: invalid RPC target ${JSON.stringify(`${channel}/${endpoint}`)}`)
  }

View on GitHub (pinned to b150a551b8)